Changes in Cloud SDK 0.9.76 for Go on Managed VM apps

[Glenn Lewis]

With the release of Cloud SDK 0.9.76, the default Dockerfile base image for "runtime: go" has been updated.

It no longer performs "go get" to resolve any dependencies that were not bundled into the Docker image.

To deploy a Go app, use the  aedeploy tool (https://godoc.org/google.golang.org/appengine/cmd/aedeploy), which will correctly assemble your app's dependencies in the same way that the go tool does. Install it by running

  $ go get google.golang.org/appengine/cmd/aedeploy

and deploy your app by prefixing a `gcloud app deploy` command with aedeploy, like

  $ aedeploy gcloud preview app deploy ./app.yaml --set-default --version demo --docker-build=remote

It is good practice (though not required) to vendor your dependencies, since that keeps your dependencies stable. If you do, still use aedeploy.

-- Glenn